Golden finger is a commonly used method for hardware connection in the computer hardware industry, which is used, for example, in the memory bank, the PC boards and so on, i.e., some bonding pads are made onto a PCB directly, then the PCB is directly inserted to a connector in which the reeds snap to the bonding pads of the PCB, so as to ensure an electrical connection. In order to increase abrasion resistance and stability, a gold plating process is applied on the bonding pads of the PCB, such that the bonding pads are referred to as the golden finger.
In recent years, the application of the golden finger is extended to the non-computer industries such as the communication industry. For example, the golden finger as a connection manner has been early or late employed in the AMC (Advanced Mezzanine Card) standard, the ATCA (Advanced Telecommunications Computing Architecture) standard and the MicroTCA (Micro Telecommunications Computing Architecture) standard established by the PICMG (PCI Industrial Computer Manufacturers Group).
As the increased application of the golden finger in the non-computer industries, some inherent problems of the golden finger connection emerge, one of which is that, since the number of times of the reliable inserting/removing operations required in the non-computer industries is much greater than that required in the computer industry (for example, the AMC standard specifies the number of times of the reliable inserting/removing operations is 200, while that required by the computer products is normally less than 20), a more tight cooperation between the connector and the golden finger is required, which will result in an excessive inserting/removing force.
Although having recognized the problem, what the standard organization can do is only to loose the standard of the allowable inserting force rather than to provide a solution to reduce the inserting/removing force, for example, the AMC standard specifies that as long as the maximum inserting force is less than 100 N, it is regarded as qualified, however, the inserting force for fitting the PCB of the golden finger connector in the prior art is more than 50 N. The inserting force will be doubled for the PCB with two connectors, and tripled for three connectors. According to the MicroTCA standard, there are 4 connectors on the MCH (MicroTCA carrier hub), thus the thrust force will be quadrupled, which has gone beyond the manual operation limitation. As the wide applications of the MicroTCA standard, the problem will emerge definitely.
An investigation shows that the reason of the excessive inserting force of the golden finger lies in that the connector reeds (spring leaves) are required to resist the opening force of the reeds of the golden finger when fitting with the golden finger. However, according to the current standards (AMC, MicroTCA, etc.), both the connectors and the PCBs have a right angle structure, and all of the golden fingers are opened at the same time, thus there will generate an extreme peak thrust force at the moment of fitting. For example, for the AMC standard, there are 170 reeds, thus the instantaneous maximum thrust force is 170 times of that of a single reed.
FIG. 1 is the schematic diagram showing the fitting between the golden finger and the connector in the prior art, wherein two golden fingers 101 and 103 are shown to be un-overlapped and in different planes for clarity. The two golden fingers 101 and 103 respectively contact with two reeds 201, 203 of the connector 200 at the same time, the thrust force at this time is twice of the thrust force of the single golden finger.
After the reeds open, the thrust force is used to counteract the sliding friction force, and the required thrust force is substantially reduced at this time. Therefore, as to the problem of the excessive thrust force, it is necessary to solve the tremendous thrust force required when the golden fingers open.